This invention relates to a release mechanism for use in wells, such as oil and gas wells, and more particularly to a release mechanism for production tubing located below subsurface control safety valves.
The mineral exploration and production industry routinely uses subsurface control safety valves for control of fluid flow, such as oil and gas in the tubing positioned in a well bore. Many such valves are hydraulically operated pistons for holding the valves open in response to hydraulic fluid pressure in the downhole tubing. Should any damage occur to valve or in the tubing below the subsurface control safety valve, an operator must stop the production flow and pull out the entire production tubing string to change the damaged valve, as well as any other components that became damaged.
The same situation exists for other production tubing equipment: should one of the production tubing mechanisms is damaged, substantial time is spent in closing the faulty mechanism and then raising up the entire production string and/or drill string to change the damaged piece of equipment. This equipment is usually located thousands of feet below the surface and when a change of the damaged equipment becomes necessary, the well operator usually constructs a large derrick suitable for lifting the production string from the wellbore.
The present invention contemplates elimination of drawbacks associated with conventional practices and provision of a hydraulic release mechanism that can be mounted below subsurface control safety valves or other similar mechanisms to close off the production string and allow only the portion of the production string above the release mechanism to be removed for repair or replacement.